1. Field of the Invention
The invention relates to an MR system for interventional procedures, including an MR imaging device which is arranged to acquire images of a part of an object and includes a magnet for generating a steady magnetic field, a gradient system for generating temporary magnetic gradient fields, and an interventional instrument or device, for example, a catheter, which includes means for generating an additional magnetic field. This invention also relates to an interventional instrument for cooperation with MR imaging device.
2. Description of the Related Art
An MR system of this kind is known from U.S. Pat. No. 4,572,198. In the known MR system the catheter is positioned, in cooperation with the MR device, so as to subject the object to an interventional procedure for which the catheter has been designed. This is, for example balloon angioplasty of a patient. Furthermore, in the known MR system the image processing unit determines the position of the catheter tip in the object on the basis of two successive MR images of the patient. The additional magnetic field is then switched off during the generating of the MR signals for the reconstruction of a first image, whereas it is switched on during the generating of the MR signals for the reconstruction of a next MR image. The additional magnetic field generated by a coil provided in the catheter tip disturbs the magnetic fields generated by the MR device, so that a difference arises between the two MR images. The processing unit determines the position of the catheter tip on the basis of the difference between the two MR images. Subsequently, via a cursor the position of the catheter tip is superposed on the MR image of the body so as to be displayed on a monitor.
It is a drawback of the known system that only the catheter tip is imaged in an MR image.